US10270387B2 - Photovoltaic module - Google Patents

Abstract

A photovoltaic module includes: a solar cell module including a plurality of solar cells; and a junction box including a capacitor unit attached to one face of the solar cell module and that to stores DC power supplied from the solar cell module, and a dc/dc converter unit to convert the level of the stored DC power and output the same. Thus, power may be easily supplied through the junction box.

Description

This application is a continuation of U.S. application Ser. No. 13/427,139 filed on Mar. 22, 2012, now allowed, which claims priority of Korean Application No. 10-2011-0033728, filed on Apr. 12, 2011, all of which are incorporated by reference in their entirety herein.

CROSS-REFERENCE TO RELATED APPLICATION

This application claims the priority benefit of Korean Patent Application No. 10-2011-0033728, filed on Apr. 12, 2011, in the Korean Intellectual Property Office, the disclosure of which is incorporated herein by reference.

BACKGROUND

1. Field of the Disclosure

The present disclosure relates to a photovoltaic module (or a solar module) and, more particularly, to a photovoltaic module capable of easily supplying power

2. Description of the Related Art

Recently, as existing energy resources such as oil or coal are expected to be exhausted, an interest in alternative energy for replacing oil or coal is increasing. In particular, a solar cell which directly converts (or transforms) solar energy into electric energy by using a semiconductor element is getting the spotlight as a next-generation cell.

Meanwhile, a photovoltaic module refers to a device in which solar cells for photovoltaic power generation are connected in series or in parallel, and the photovoltaic module may include a junction box collecting electricity produced by the solar cells.

SUMMARY

one aspect provides a photovoltaic module capable of easily supply power through a junction box.

Another aspect provides a photovoltaic module which may be easily installed and is advantageous for increasing capacity in constituting a system.

According to another aspect, there is provided a photovoltaic module including: a solar cell module including a plurality of solar cells; and a junction box including a capacitor unit attached to one face of the solar cell module and that stores DC power supplied from the solar cell module, and a dc/dc converter unit to convert the level of the stored DC power and output the same.

According to yet another aspect, there is provided a photovoltaic module including: a solar cell module including a plurality of solar cells; and a junction box including a bypass diode attached to one face of the solar cell module and that bypasses a solar cell in which a reverse voltage occurs among the plurality of solar cells, a capacitor unit to store DC power supplied from the solar cell module, a dc/dc converter unit to convert the level of the stored DC power and output the same, and an inverter unit to convert power into AC power and output the same.

The foregoing and other objects, features, aspects and advantages according to the disclosure will become more apparent from the following detailed description when taken in conjunction with the accompanying drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a front view of a photovoltaic module according to an embodiment of the present invention.

FIG. 2 is a rear view of the photovoltaic module ofFIG. 1.

FIG. 3 is an exploded perspective view of the photovoltaic module ofFIG. 1.

FIG. 4 is a view showing an example of bypass diodes of the photovoltaic module ofFIG. 1.

FIG. 5 is a view showing an example of an internal circuit diagram of a junction box of the photovoltaic module according to an embodiment of the invention.

FIG. 6 is a view showing another example of an internal circuit diagram of a junction box of the photovoltaic module according to another embodiment of the invention.

FIG. 7 is a view showing an example of a circuit diagram related to a capacitor unit according to an embodiment of the invention.

FIG. 8 is a view showing an example of the configuration of a photovoltaic system.

FIG. 9 is a view showing another example of the configuration of a photovoltaic system.

FIGS. 10A and 10B are schematic diagrams referred to explain power optimizing of the photovoltaic system according to an embodiment of the present invention.

DETAILED DESCRIPTION

Exemplary embodiments of the present invention will now be described in detail with reference to the accompanying drawings.

In the following description, usage of suffixes such as ‘module’, ‘part’ or ‘unit’ used for referring to elements is given merely to facilitate explanation of the present disclosure, without having any significant meaning in itself. Thus, the ‘module’ and ‘part’ may be interchangeably used.

FIG. 1 is a front view of a photovoltaic module according to an embodiment of the present invention.FIG. 2 is a rear view of the photovoltaic module ofFIG. 1.FIG. 3 is an exploded perspective view of the photovoltaic module ofFIG. 1.

With reference toFIGS. 1 to 3, aphotovoltaic module50 according to an embodiment of the present invention includes asolar cell module100 and ajunction box200 positioned on one surface of thesolar cell module100. Thesolar cell module50 may further include a heat releasing member (not shown) disposed between thesolar cell module100 and thejunction box200.

Thesolar cell module100 may include a plurality ofsolar cells130. Also, thesolar cell module100 may further include afirst sealing member120 and asecond sealing member150 positioned on lower and upper surfaces of the plurality ofsolar cells130, arear substrate110 positioned on a lower surface of thefirst sealing member120, and afront substrate160 positioned on an upper surface of thesecond sealing member150.

Each of thesolar cells130 is a semiconductor device converting solar energy into electric energy and may be a silicon solar cell, a compound semiconductor solar cell, a tandem solar cell, a dye-sensitized solar cell, a CdTe or CIGS type solar cell, or the like.

Each of thesolar cells130 is configured to have a light receiving face to which solar light is made incident and a rear face, which is opposite to the light receiving face. For example, each of thesolar cells130 may include a silicon substrate having a first conductivity type, a semiconductor layer formed on the silicon substrate and having a second conductivity type which is opposite to the first conductivity type, an anti-reflective film having one or more openings that expose a portion of the second conductivity type semiconductor layer and formed on the second conductivity type semiconductor layer, a front electrode in contact with the portion of the second conductivity type semiconductor layer through the one or more openings, and a rear electrode formed on a rear surface of the silicon substrate.

The respectivesolar cells130 may be electrically connected in series, in parallel, or in series and parallel. In detail, the plurality ofsolar cells130 may be electrically connected by aribbon133. Theribbon133 may be bonded to the front electrode formed on a light receiving face of a solar cell and to the rear electrode formed on a rear surface of an adjacentsolar cell130.

In the drawing, it is illustrated that theribbons133 are formed in two rows, and thesolar cells130 are connected in a row by theribbons133, formingsolar cell strings140. Accordingly, sixstrings140a,140b,140c,140d,140e, and140fare formed, and each string includes ten solar cells. However, various modifications may be made, unlike that of the drawing.

Meanwhile, the respective solar cell strings may be electrically connected by bus ribbons.FIG. 1 illustrates that the firstsolar cell string140aand the secondsolar cell string140b, the thirdsolar cell string140cand the fourthsolar cell string140d, and the fifthsolar string140eand the sixthsolar cell string140fare electrically connected bybus ribbons145a,145c, and145edisposed at a lower portion of thesolar cell module100, respectively. Also,FIG. 1 illustrates that the secondsolar cell string140band the thirdsolar cell string140c, and the fourthsolar cell string140dand the fifthsolar cell string140eare electrically connected bybus ribbons145band145ddisposed at an upper portion of thesolar cell module100, respectively.

Meanwhile, the ribbon connected to the first string, the bus ribbons145band145d, and the ribbon connected to the sixth string are electrically connected to the first to fourthconductive lines135a,135b,135c, and135d, respectively, and the first to fourthconductive lines135a,135b,135c, and135dare connected with bypass diodes Da, Db, and Dc (see, for example,FIG. 4) within thejunction box200 disposed on the rear surface of thesolar cell module100. In the drawing, it is illustrated that the first to fourthconductive lines135a,135b,135c, and135dextend to the rear surface of thesolar cell module100 through openings formed on thesolar cell module100.

Meanwhile, preferably, thejunction box200 is disposed to be adjacent to be closer to an end portion, among both end portions of thesolar cell module100, where the conductive lines extend.

InFIGS. 1 and 2, the first to fourthconductive lines135a,135b,135c, and135dextend from the upper portion of thesolar cell module100 to the rear surface of thesolar cell module100, so thejunction box200 is illustrated to be positioned at the upper portion of the rear surface of thesolar cell module100. Accordingly, the length of the conductive lines may be reduced, and thus, a power lost may be reduced.

Unlike the configuration illustrated inFIGS. 1 and 2, if the first to fourthconductive lines135a,135b,135c, and135dextend from the lower portion of thesolar cell module100 to the rear surface of thesolar cell module100, thejunction box200 may be positioned at a lower portion of the rear surface of thesolar cell module100.

Therear substrate110, as a back sheet, performs functions such as waterproofing, insulating, and filtering of ultraviolet rays. Therear substrate110 may be a TPT (Tedlar/PET/Tedlar) type rear substrate, but is not meant to be limited thereto. Also, inFIG. 3, therear substrate110 has a rectangular shape but it may be fabricated to have various shapes such as a circular shape, a semi-circular shape, or the like, according to an environment in which thesolar cell module100 is installed.

Meanwhile, thefirst sealing member120 may have the same size as that of therear substrate110 and attached to therear substrate110, and the plurality ofsolar cells130 may be positioned to adjoin each other in several number of rows on thefirst sealing member120.

Thesecond sealing member150 is positioned on thesolar cells130 and may be bonded to the first sealingmember120 through lamination.

Here, thefirst sealing member120 and thesecond sealing member150 may enable respective elements of the solar cells to be chemically bonded. Thefirst sealing member120 and thesecond sealing member150 may be, for example, an ethylene vinyl acetate (EVA) film, or the like.

Meanwhile, preferably, thefront substrate160 is positioned on thesecond sealing member150 to allow solar light to be transmitted therethrough, and may be tempered glass in order to protect thesolar cells130 against external impact, or the like. Also, more preferably, in order to prevent a reflection of solar light and increase transmittance of solar light, the front substrate may be a low iron tempered glass including a small amount of iron.

Thejunction box200 is attached to the rear surface of thesolar cell module100, and may convert power by using DC power supplied from thesolar cell module100. In detail, thejunction box200 may include a capacitor unit (520 inFIG. 5) for storing DC power and a dc/dc converter unit (530 inFIG. 5) for converting the level of the DC power and outputting the same. Also, thejunction box200 may further include bypass diodes Da, Db, and Dc (510 inFIG. 5) for preventing a back flow of current among solar cell strings. Also, thejunction box200 may further include an inverter unit (540 inFIG. 5) for converting DC power into AC power. This will be described later with reference toFIG. 5.

In this manner, thejunction box200 according to an embodiment of the present invention may include at least the bypass diodes Da, Db, and Dc, the capacitor unit for storing DC power, and the dc/dc converter unit.

When thejunction box200 is integrally formed with thesolar cell module100, a loss of DC power generated by eachsolar cell module100 may be minimized and effectively managed, like a solar photovoltaic system ofFIG. 8 or 9. Meanwhile, the integrally formedjunction box200 may be called an MIC (Module Integrated Converter).

Meanwhile, in order to prevent an infiltration of moisture to circuit elements in thejunction box200, the interior of the junction box may be coated with silicon, or the like.

Meanwhile, openings (not shown) are formed on thejunction box200 in order to allow the foregoing first to fourthconductive lines135a,135b,135c, and135dto be connected with the bypass diodes Da, Db, and Dc in thejunction box200.

When thejunction box200 operates, heat having a high temperature is generated from the bypass diodes Da, Db, and Dc, or the like. The generated heat may reduce the efficiency of particularsolar cells130 arranged at the position where thejunction box200 is attached.

Thus, in order to prevent the efficiency problem, thephotovoltaic module50 according to an embodiment of the present invention may further include a heat releasing member (not shown) disposed between thesolar cell model100 and thejunction box200. In order to dissipate heat generated by thejunction box200, preferably, the heat releasing member may have a larger sectional area than that of a plate (not shown). For example, the heat releasing member may be formed on the entirety of the rear surface of thesolar cell module100. Preferably, the heat releasing member is made of a metal material such as gold (Au), silver (Ag), copper (Cu), aluminum (Al), tungsten (W), or the like.

An external connection terminal (not shown) may be formed at one side of thejunction box160 in order to output power-converted DC power or AC power to the outside.

FIG. 4 is a view showing an example of bypass diodes of the photovoltaic module ofFIG. 1.

With reference toFIG. 4, the bypass diodes Da, Db, Dc may be connected correspondingly according to the six solar cell strings140a,140b,140c,140d,140e, and140f. In detail, the first bypass diode Da is connected between the firstsolar cell string140aand thefirst bus ribbon145bto bypass the firstsolar cell string140aand the secondsolar cell string140bwhen a reverse voltage occurs in the firstsolar cell string140aor the secondsolar cell string140b.

For example, when a voltage of about 0.6V, which is generated in a normal solar cell, is generated, the potential of a cathode electrode of the first bypass diode D1 is higher by about 12V (=0.6V*20) than that of an anode electrode of the first bypass diode D1. Namely, the first bypass diode D1 performs a normal operation, rather than a bypassing operation.

Meanwhile, when a hot spot occurs such as when shade occurs in a solar cell of the firstsolar cell string140aor when a foreign object is attached, a reverse voltage (about 15V), not the voltage of about 0.6V, is generated from the solar cell. Accordingly, the potential of the anode electrode of the first bypass diode Da is higher by about 15V than that of the cathode electrode. Then, the first bypass diode Da performs a bypassing operation. Thus, the voltage generated in the solar cells in the firstsolar cell string140aand the secondsolar cell string140bis not supplied to thejunction box200. In this manner, when a reverse voltage is generated in some of the solar cells, it is bypassed, thus preventing the corresponding solar cells, or the like, from being damaged. Also, generated DC power may be supplied, except for the hot spot area.

The second bypass diode Db is connected between thefirst bus ribbon145band thesecond bus ribbon145d, and when a reverse voltage is generated in the thirdsolar cell string140cor the fourthsolar cell string140d, the second bypass diode Db bypasses the thirdsolar cell string140cand the fourthsolar cell string140d.

The third bypass diode Dc is connected between the sixth solar cell string and thesecond bus ribbon145d, and when a reverse voltage is generated in the fifthsolar cell string140eor the sixthsolar cell string140f, the third bypass diode Dc bypasses the fifth solar cell string and the sixth solar cell string.

Meanwhile, unlike the case ofFIG. 4, six bypass diodes may be connected correspondingly according to six solar cell strings, and various other modifications may also be implemented.

FIG. 5 is a view showing an example of an internal circuit diagram of a junction box of the photovoltaic module ofFIG. 1.

With reference toFIG. 5, thejunction box200 according to an embodiment of the present invention may include abypass diode unit510, thecapacitor unit520, the dc/dc converter unit530, and theinverter unit540.

Thejunction box200 outputs AC power. Such ajunction box200 may be called a micro-inverter.

Thebypass diode unit510 includes first to third bypass diodes Da, Db, and Dc disposed between a, b, c, and d nodes which correspond to the first to fourthconductive lines135a,135b,135c, and135d, respectively.

Thecapacitor unit520 stores DC power supplied from thesolar cell module100. InFIG. 5, it is illustrated that three capacitors Ca, Cb, and Cc are connected in parallel, but the capacitor unit is not limited thereto and the three capacitors may be connected in series or may be connected in series and parallel.

According to an embodiment of the present invention, preferably, thecapacitor unit520 is detachably attached to thejunction box200. For example, each of the capacitors Ca, Cb, and Cc have a stacked structure in which they are disposed in parallel with each other within a frame. Thecapacitor unit520 may be detachably mounted as a module in a recess within thejunction box200. According to this structure, when thecapacitor unit520 is to be replaced due to its life span or when thecapacitor unit520 is broken down, thecapacitor unit520 may be easily replaced.

The dc/dc converter unit530 performs conversion of DC power level by using the DC power stored in thecapacitor unit520. InFIG. 5, a flyback converter using a turn-on timing of a switching element S1 and a winding ratio of a transformer T is illustrated. Accordingly, voltage boosting of a dc level may be performed.

Besides the flyback converter illustrated inFIG. 5, a boost converter, a buck converter, a forward converter, or the like, may also be used as the dc/dc converter unit530, or a combination thereof (e.g., a cascaded buck-boost converter, or the like) may also be used as the dc/dc converter unit530.

Theinverter unit540 converts the level-converted DC power into AC power. InFIG. 5, a full-bridge inverter is illustrated. Namely, upper arm switching elements Sa and Sb connected in series and lower arm switching elements S′a and S′b connected in series are paired, and a total of two pairs of upper and lower arm switching elements are connected in parallel (Sa&S′a, Sb&S′b). Diodes are connected reversely parallel to the respective switching elements Sa, S′a, Sb, and S′b.

The switching elements in theinverter unit540 are turned on or off based on an inverter switching control signal from an inverter controller (not shown). Accordingly, AC power having a certain frequency is outputted. Preferably, the AC power has the same frequency (about 60 Hz) as an AC frequency of grid.

Meanwhile, a capacitor unit (not shown) for storing the level-converted dc power may be further provided between the dc/dc converter unit530 and theinverter unit540. The capacitor unit (not shown) may include a plurality of capacitors, like the foregoingcapacitor unit520 does.

As shown inFIG. 5, because thejunction box200 includes the capacitor unit storing DC power, the dc/dc converter unit for converting the level of the stored DC power and outputting the same, and the inverter unit for converting the level-converted DC power into AC power and outputting the same, AC power may be simply supplied through thejunction box200. Also, the installation of thephotovoltaic module50 may be facilitated, and the capacitor may be easily increased in configuring a solar photovoltaic system including a plurality of photovoltaic modules.

FIG. 6 is a view showing another example of an internal circuit diagram of a junction box of the photovoltaic module ofFIG. 1.

With reference toFIG. 6, thejunction box200 according to an embodiment of the present invention may include thebypass diode unit510, thecapacitor unit520, and the dc/dc converter unit530. Unlike the internal circuit diagram ofFIG. 5, the internal circuit diagram ofFIG. 6 does not include theinverter unit540.

Thus, thejunction box200 may be able to output DC power. In this case, when thejunction box200 executes a power optimizing function, such ajunction box200 may be called a power optimizer.

As shown inFIG. 6, since thejunction box200 includes the capacitor unit storing DC power and the dc/dc converter unit converting the level of the stored DC power and outputting the same, the DC power may be simply supplied through thejunction box200. Also, the installation of thephotovoltaic module50 may be facilitated, and the capacitor may be easily increased in configuring a solar photovoltaic system including a plurality of photovoltaic modules.

FIG. 7 is a view showing an example of a circuit diagram related to a capacitor unit ofFIG. 5.

With reference toFIG. 7, thecapacitor unit520 stores DC power supplied from thesolar cell module100. In particular, in an initial operation, when current flows from thesolar cell module100 to thecapacitor unit520, an overcurrent such as peak current is instantly generated. Then, the capacitor elements Cl, Cb, and Cc within thecapacitor unit520 are highly likely to be damaged.

In an embodiment of the present invention, in order to prevent an introduction of an inrush current or an overcurrent, anovercurrent preventing unit515 is disposed between thebypass diode unit510 and thecapacitor unit520, and acontroller550 may be further provided to control theovercurrent preventing unit515. Namely, thejunction box200 may further include anovercurrent preventing unit515 and acontroller550.

Theovercurrent preventing unit515 may include a first switching element Sf1 turned on during the initial operation, a second switching element Sf2 turned on after the initial operation, and a resistor element Rf connected in series to the first switching element Sf1.

For example, during the first operation, when the first switching element Sf1 is turned on, an input overcurrent component is partially consumed in the resistor element Rf and stored in thecapacitor unit520.

Next, when the second switching element Sf2 is turned on after the initial operation, the DC power supplied from thesolar cell module100 is stored in thecapacitor unit520.

Meanwhile, a first current detection unit A detects current ic1 flowing to thecapacitor unit520, and a voltage detection unit B detects voltage vc1 stored in thecapacitor unit520. The detected current ic1 and the voltage vc1 are inputted to thecontroller550.

Also, the second current detection unit C detects current ic2 supplied to the dc/dc converter unit530. The detected current ic2 is inputted to thecontroller550.

Thecontroller550 outputs turn-on timing signals Sc1 and Sc2 of the first switching element Sf1 and the second switching element Sf2 based on the detected current ic1 or ic2 or the voltage vc1.

For example, when the detected current ic1 or ic2 or the voltage vc1 is higher than a pre-set value, thecontroller550 may turn off the first switching element Sf1 and turn on the second switching element Sf2.

Meanwhile, when the detected current ic1 or ic2 or the voltage vc1 is higher than an allowable value, thecontroller550 may turn off both the first switching element S1 and the second switching element Sf2 to prevent supply of DC power supplied from thesolar cell module100 to thecapacitor unit520.

Meanwhile, thecontroller550 may output a converter control signal for controlling the switching element of the dc/dc converter unit530 ofFIG. 5. Also, thecontroller550 may output an inverter control signal for controlling the switching elements of theinverter unit540.

Meanwhile, thecontroller550 may control the switching element of the dc/dc converter unit530 ofFIG. 5 to perform power optimizing (to be described).

Meanwhile, theovercurrent preventing unit515 and thecontroller550 may applicable to the junction box ofFIG. 6 as well as to the junction box ofFIG. 5.

FIG. 8 is a view showing an example of the configuration of a photovoltaic system.

With reference toFIG. 8, the solar photovoltaic system according to an embodiment of the present invention may include a plurality ofphotovoltaic modules50a,50b, . . . ,50n. Thephotovoltaic modules50a,50b, . . . ,50nmay includejunction boxes200a,200b, . . . ,200noutputting AC power, respectively. In this case, thejunction boxes200a,200b, . . . ,200nmay be micro-inverters, and AC power output from therespective junction boxes200a,200b, . . . ,200nis supplied to a grid.

Meanwhile, the internal circuit of thejunction box200 illustrated inFIG. 5 according to an embodiment of the present invention may be applied to the micro-inverter ofFIG. 8.

FIG. 9 is a view showing another example of the configuration of a solar photovoltaic system according to an embodiment of the present invention.

With reference toFIG. 9, the solar photovoltaic system according to an embodiment of the present invention may include a plurality ofphotovoltaic modules50a,50b, . . . ,50n. Thephotovoltaic modules50a,50b, . . . ,50nmay includejunction boxes1200a,1200b, . . . ,1200noutputting DC power, respectively. Also, aninverter unit1210 for converting DC power output from the respectivephotovoltaic modules50a,50b, . . . ,50ninto AC power may be further provided. In this case, thejunction boxes1200a,1200b, . . . ,1200nmay perform power optimizing in order to effectively output DC power.

Meanwhile, the internal circuit of thejunction box200 ofFIG. 6 according to an embodiment of the present invention may be applied to the power optimizer ofFIG. 9.

FIGS. 10A and 10B are schematic diagrams referred to in explaining power optimizing of the solar photovoltaic system according to an embodiment of the present invention.

First, a case in which power optimizing is not employed will now be described with reference toFIG. 10A. As illustrated, in a state in which a plurality of solar cell modules are connected in series, when a hot spot occurs insolar cell modules1320 so that a power loss is made (e.g., 70 W power supply), a power loss is also made even in a normal solar cell module1310 (e.g., 70 W power supply). Thus, only power totaling 980 W is supplied.

Next, a case in which power optimizing is employed will now be described with reference toFIG. 10B. When a hot spot occurs insolar cell modules1320 so that a power loss is made (e.g., 70 W power supply), voltage output from the correspondingsolar cell modules1320 is lowered so that current supplied from the correspondingsolar cell modules1320 may be equal to the current supplied from a differentsolar cell module1310. Thus, although a power loss (e.g., 70 W power supply) is made in thesolar cell modules1320 in which a hot spot occurs, there is no power loss in the normal solar cell module1310 (e.g., 100 W power supply). Thus, power totaling 1340 W may be supplied.

Through power optimizing, the voltage supplied from a solar cell module in which a hot spot occurs may be adjusted according to the current supplied from a different solar cell module. To this end, each of the solar cell modules, in particular, thecontroller550 of each of the solar cell modules, may control a voltage output, or the like, of its own upon receiving a current value or a voltage value supplied from a different solar cell module.

Meanwhile, thejunction box200 illustrated inFIG. 6 according to an embodiment of the present invention may be applicable to the power optimizing ofFIG. 10B.

According to embodiments of the present invention, since the junction box includes the capacitor unit storing DC power and the dc/dc converter converting the level of the stored DC power and outputting the same, power may be easily supplied through the junction box.

Also, the photovoltaic module having such a junction box may be easily installed, and when a solar photovoltaic system including a plurality of photovoltaic modules is configured, the capacity may be easily increased.

Meanwhile, since the junction box includes the capacitor unit storing DC power, the dc/dc converter unit converting the level of the stored DC power and outputting the same, and the inverter unit converting the level-converted DC power into AC power and outputting the same, AC power may be simply supplied through the junction box.

Also, since the capacitor unit is detachably mounted, when the capacitor unit is defective, it may be easily replaced.

The photovoltaic module according to the embodiments of the present disclosure is not limited in its application of the configurations and methods, but the entirety or a portion of the embodiments may be selectively combined to be configured into various modifications.

As the present invention may be embodied in several forms without departing from the characteristics thereof, it should also be understood that the above-described embodiments are not limited by any of the details of the foregoing description, unless otherwise specified, but rather should be construed broadly within its scope as defined in the appended claims, and therefore all changes and modifications that fall within the metes and bounds of the claims, or equivalents of such metes and bounds are therefore intended to be embraced by the appended claims.

Claims (16)

What is claimed is:

1. A photovoltaic module comprising:

a solar cell module including a plurality of solar cell strings formed with some of a plurality of solar cells, a plurality of bus ribbons connecting adjacent solar cell strings, and a plurality of conductive lines electrically connecting the solar cell strings and a plurality of bypass diodes; and

a junction box disposed on a rear surface of the solar cell module, the junction box comprising:

the plurality of bypass diodes;

a capacitor unit to store DC power supplied from the solar cell module;

a dc/dc converter to convert a level of stored DC power to a level-converted DC power and output the same;

a switching circuit to supply DC power supplied from the solar cell or to stop supplying DC power supplied from the solar cell;

a first current detector to detect a current supplied to the capacitor unit;

a voltage detector to detect a voltage at the capacitor unit; and

a controller to control the switching circuit to stop supplying the DC power when the detected current or the detected voltage is not within an allowable range,

wherein the plurality of conductive lines are connected with the plurality of bypass diodes and are extended to the rear surface of the solar cell module through corresponding openings penetrating the rear substrate of the solar cell module,

wherein the capacitor unit comprises a plurality of capacitors connected in parallel, in series, or in series and parallel, and the plurality of capacitors are disposed in a stacked structure within a frame,

wherein the capacitor unit is detachably mounted as a separate module in a recess within the junction box, and

wherein the switching circuit comprises:

a first switching element and a second switching element between the plurality of bypass diodes and the capacitor unit, the first switching element and the second switching element being connected in parallel; and

a resistor connected to the first switching element,

wherein the first switching element is turned on during an initial operation and the second switching element is turned on after the initial operation, and

wherein when the detected current or the detected voltage is greater than a pre-set value, the controller controls the first switching element to be turned off and the second switching element to be turned on.

2. The photovoltaic module ofclaim 1, wherein the plurality of bypass diodes bypass at least one solar cell in which a reverse voltage occurs among the plurality of solar cells.

3. The photovoltaic module ofclaim 1, wherein the controller outputs switching signals of the first switching element and the second switching element based on detected current from the first current detector or detected voltage from the voltage detector, and

wherein when the detected current or the detected voltage is not within the allowable range, the controller controls the first switching element and the second switching element to be turned off.

4. The photovoltaic module ofclaim 1, wherein the dc/dc converter comprises at least one of a flyback converter, a boost converter, a buck converter, and a forward converter.

5. The photovoltaic module ofclaim 1, wherein the junction box further comprises:

a second current detection unit to detect a current supplied to the dc/dc converter.

6. The photovoltaic module ofclaim 1, further comprising:

a heat releasing member between the solar cell module and the junction box.

7. The photovoltaic module ofclaim 1, wherein the switching circuit is between the plurality of bypass diodes and the capacitor unit.

8. The photovoltaic module ofclaim 1, wherein one of the plurality of conductive lines connects one of the plurality of solar cell strings and one of the plurality of bypass diodes, and

wherein a first end of one of the plurality of conductive lines is connected to one of the plurality of bus ribbons, and a second end of the one of the plurality of conductive lines is connected to one of the plurality of bypass diodes.

9. The photovoltaic module ofclaim 1, wherein the solar cell module further comprises:

first and second sealing members on upper and lower surfaces of the plurality of solar cells, respectively;

the rear substrate on a lower surface of the first sealing member; and

a front substrate on an upper surface of the second sealing member.

10. The photovoltaic module ofclaim 1, wherein the solar cell module further comprises:

a solar cell string formed with some of the plurality of solar cells connected in a row, and a first conductive line electrically connecting the solar cell string and the junction box.

11. The photovoltaic module ofclaim 10, wherein the solar cell module further comprises:

a bus ribbon connected to at least two solar cell strings; and

a second conductive line electrically connecting the bus ribbon and the junction box.

12. The photovoltaic module ofclaim 11, wherein the junction box is closer to an end portion, to which the conductive line extends, between two end portions of the solar cell module.

13. A photovoltaic module comprising:

a solar cell module including a plurality of solar cell strings formed with some of a plurality of solar cells, a plurality of bus ribbons connecting adjacent solar cell strings, and a plurality of conductive lines electrically connecting the solar cell strings and a plurality of bypass diodes; and

a junction box disposed on a rear surface of the solar cell module, the junction box comprising:

the plurality of bypass diodes to bypass at least one solar cell in which a reverse voltage occurs among the plurality of solar cells,

a capacitor unit to store DC power supplied from the solar cell module, the capacitor unit detachable from the junction box;

a dc/dc converter to convert a level of the stored DC power to a level-converted DC power and output the same,

an inverter unit to convert the level-converted DC power into AC power and output the same,

a switching circuit to limit a current based on a DC current supplied from the solar cell module, and

a first current detector to detect a current supplied to the capacitor unit;

a voltage detector to detect a voltage at the capacitor unit;

a controller to control the switching circuit and to stop supplying of the DC power when the detected current or the detected voltage is not within an allowable range,

wherein the plurality of conductive lines are connected with the plurality of bypass diodes and are extended to the rear surface of the solar cell module through corresponding openings penetrating the rear substrate of the solar cell module,

wherein the capacitor unit comprises a plurality of capacitors connected in parallel, in series, or in series and parallel, and the plurality of capacitors are disposed in a stacked structure within a frame,

wherein the capacitor unit is detachably mounted as a separate module in a recess within the junction box, and

wherein the switching circuit comprises:

a first switching element and a second switching element between the plurality of bypass diodes and the capacitor unit, the first switching element and the second switching element being connected in parallel; and

a resistor connected to the first switching element,

wherein the first switching element is turned on during an initial operation and the second switching element is turned on after the initial operation, and

wherein when the detected current or the detected voltage is greater than a pre-set value, the controller controls the first switching element to be turned off and the second switching element to be turned on.

14. The photovoltaic module ofclaim 13, wherein the controller outputs switching signals of the first switching element and the second switching element based on detected current from the first current detector or detected voltage from the voltage detector, and

wherein when the detected current or the detected voltage is not within the allowable range, the controller controls the first switching element and the second switching element to be turned off.

15. The photovoltaic module ofclaim 13, further comprising:

a second current detection unit to detect a current supplied to the dc/dc converter,

wherein the controller controls the switching circuit based on the detection of the second current detection unit.

16. The photovoltaic module ofclaim 13, wherein one of the plurality of conductive lines connects one of the plurality of solar cell strings and one of the plurality of bypass diodes, and

wherein a first end of one of the plurality of conductive lines is connected to one of the plurality of bus ribbons, and a second end of the one of the plurality of conductive lines is connected to one of the plurality of bypass diodes.

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